I. Field of the Invention
This invention relates generally to wireless communication systems and more particularly to physical-layer signal processing in a millimeter-wave wireless communication system.
II. Description of the Related Art
In one aspect of the related art, a dual-mode ultra-wideband (UWB) Physical Layer supporting single carrier and OFDM modulation employs a common mode. The UWB Physical Layer may be used for millimeter wave (e.g., 60 GHz) communications. Specifically, the document IEEE P802.15.3.c/D00, “Part 15.3: Wireless Medium Access Control (MAC) and Physical Layer (PHY) Specifications for High Rate Wireless Personal Area Networks (WPANs): Amendment 2: Millimeter-wave based Alternative Physical Layer Extension,” is incorporated herein by reference in its entirety.
The common mode is a single-carrier mode used by both single-carrier and OFDM devices for beaconing, network-control signaling, and base-rate data communications. The common mode is typically necessary for interoperability between different devices and different networks.
For low-power devices, it is advantageous for the common mode to employ a continuous phase modulated (CPM) signal having a constant envelope so that power amplifiers can be operated at maximum output power without affecting the spectrum of the filtered signal. Gaussian minimum shift keying (GMSK) is a form of continuous phase modulation having compact spectral occupancy by choosing a suitable bandwidth time product (BT) parameter in a Gaussian filter. The constant envelope makes GMSK compatible with nonlinear power amplifier operation without the concomitant spectral re-growth associated with non-constant envelope signals.
Various techniques may be implemented to produce GMSK pulse shapes. For example, π/2-binary phase shift key (BPSK) modulation (or π/2-differential BPSK) with a linearized GMSK pulse may be implemented, such as shown in I. Lakkis, J. Su, & S. Kato, “A Simple Coherent GMSK Demodulator”, IEEE PIMRC 2001, which is incorporated by reference herein.